 /*******************************************************************************
  * Copyright (c) 2004, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.handlers;

 import java.lang.reflect.InvocationTargetException ;
 import java.lang.reflect.Method ;

 import org.eclipse.core.commands.ExecutionEvent;
 import org.eclipse.core.commands.ExecutionException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.internal.ExceptionHandler;

 /**
  * This handler is an adaptation of the widget method handler allowing select
  * all to work even in some cases where the "selectAll" method does not exist.
  * This handler attempts to use "getTextLimit" and "setSelection" to do select
  * all. If this doesn't work, then it finally fails.
  *
  * @since 3.0
  */
 public class SelectAllHandler extends WidgetMethodHandler {

     /**
      * The parameters for a single point select all.
      */
     private static final Class [] METHOD_PARAMETERS = { Point.class };

     public final Object execute(final ExecutionEvent event)
             throws ExecutionException {
         final Method methodToExecute = getMethodToExecute();
         if (methodToExecute != null) {
             try {
                 final Control focusControl = Display.getCurrent()
                         .getFocusControl();
                 
                 final int numParams = methodToExecute.getParameterTypes().length;

                 if ((focusControl instanceof Composite)
                         && ((((Composite) focusControl).getStyle() & SWT.EMBEDDED) != 0)) {
                     
                     // we only support selectAll for swing components
 if (numParams != 0) {
                         return null;
                     }

                     /*
                      * Okay. Have a seat. Relax a while. This is going to be a
                      * bumpy ride. If it is an embedded widget, then it *might*
                      * be a Swing widget. At the point where this handler is
                      * executing, the key event is already bound to be
                      * swallowed. If I don't do something, then the key will be
                      * gone for good. So, I will try to forward the event to the
                      * Swing widget. Unfortunately, we can't even count on the
                      * Swing libraries existing, so I need to use reflection
                      * everywhere. And, to top it off, I need to dispatch the
                      * event on the Swing event queue, which means that it will
                      * be carried out asynchronously to the SWT event queue.
                      */
                     try {
                         final Object focusComponent = getFocusComponent();
                         if (focusComponent != null) {
                             Runnable methodRunnable = new Runnable () {
                                 public void run() {
                                     try {
                                         methodToExecute.invoke(focusComponent,
                                                 null);
                                         // and back to the UI thread :-)
 focusControl.getDisplay().asyncExec(
                                                 new Runnable () {
                                                     public void run() {
                                                         if (!focusControl
                                                                 .isDisposed()) {
                                                             focusControl
                                                                     .notifyListeners(
                                                                             SWT.Selection,
                                                                             null);
                                                         }
                                                     }
                                                 });
                                     } catch (final IllegalAccessException e) {
                                         // The method is protected, so do
 // nothing.
 } catch (final InvocationTargetException e) {
                                         /*
                                          * I would like to log this exception --
                                          * and possibly show a dialog to the
                                          * user -- but I have to go back to the
                                          * SWT event loop to do this. So, back
                                          * we go....
                                          */
                                         focusControl.getDisplay().asyncExec(
                                                 new Runnable () {
                                                     public void run() {
                                                         ExceptionHandler
                                                                 .getInstance()
                                                                 .handleException(
                                                                         new ExecutionException(
                                                                                 "An exception occurred while executing " //$NON-NLS-1$
 + methodToExecute
                                                                                                 .getName(),
                                                                                 e
                                                                                         .getTargetException()));
                                                     }
                                                 });
                                     }
                                 }
                             };

                             swingInvokeLater(methodRunnable);
                         }
                     } catch (final ClassNotFoundException e) {
                         // There is no Swing support, so do nothing.

                     } catch (final NoSuchMethodException e) {
                         // The API has changed, which seems amazingly unlikely.
 throw new Error ("Something is seriously wrong here"); //$NON-NLS-1$
 }
                 } else if (numParams == 0) {
                     // This is a no-argument selectAll method.
 methodToExecute.invoke(focusControl, null);
                     focusControl.notifyListeners(SWT.Selection, null);

                 } else if (numParams == 1) {
                     // This is a single-point selection method.
 final Method textLimitAccessor = focusControl.getClass()
                             .getMethod("getTextLimit", NO_PARAMETERS); //$NON-NLS-1$
 final Integer textLimit = (Integer ) textLimitAccessor
                             .invoke(focusControl, null);
                     final Object [] parameters = { new Point(0, textLimit
                             .intValue()) };
                     methodToExecute.invoke(focusControl, parameters);
                     focusControl.notifyListeners(SWT.Selection, null);

                 } else {
                     /*
                      * This means that getMethodToExecute() has been changed,
                      * while this method hasn't.
                      */
                     throw new ExecutionException(
                             "Too many parameters on select all", new Exception ()); //$NON-NLS-1$

                 }

             } catch (IllegalAccessException e) {
                 // The method is protected, so do nothing.

             } catch (InvocationTargetException e) {
                 throw new ExecutionException(
                         "An exception occurred while executing " //$NON-NLS-1$
 + getMethodToExecute(), e.getTargetException());

             } catch (NoSuchMethodException e) {
                 // I can't get the text limit. Do nothing.

             }
         }

         return null;
     }

     /**
      * Looks up the select all method on the given focus control.
      *
      * @return The method on the focus control; <code>null</code> if none.
      */
     protected Method getMethodToExecute() {
         Method method = super.getMethodToExecute();

         // Let's see if we have a control that supports point-based selection.
 if (method == null) {
             final Control focusControl = Display.getCurrent().getFocusControl();
             if (focusControl != null) {
                 try {
                     method = focusControl.getClass().getMethod("setSelection", //$NON-NLS-1$
 METHOD_PARAMETERS);
                 } catch (NoSuchMethodException e) {
                     // Do nothing.
 }
             }
         }

         return method;
     }

     /**
      * @see org.eclipse.core.runtime.IExecutableExtension#setInitializationData(org.eclipse.core.runtime.IConfigurationElement,
      * java.lang.String, java.lang.Object)
      */
     public void setInitializationData(IConfigurationElement config,
             String propertyName, Object data) {
         // The name is always "selectAll".
 methodName = "selectAll"; //$NON-NLS-1$
 }
 }

